Hard to swallow: June 2005
'The anti-impotence drug Viagra can protect mountaineers from developing lung problems sometimes associated with high altitude'; so say researchers at the University of Geissen in Germany.
The study, in the Annals of Internal Medicine, discovered that Viagra triggered an increase in the amount of blood travelling through the lung vessels and thus prevented the onset of pulmonary hypertension, a heart and lung condition caused by lack of oxygen. The condition causes the constriction of blood vessels in the lungs, meaning that the heart is forced to work harder, and can eventually lead to permanent heart damage or even death. The researchers used climbers to test how effective Viagra was in relieving the condition: 14 healthy male mountaineers were given either Viagra (sildenafil) or a dummy pill and tested at both sea level and at high altitude - the Mount Everest base camp. Sildenafil was found to reduce high blood pressure and improve the transport of oxygen in the blood in both situations. Researchers say that it is the first drug to be shown to increase the capacity to exercise at sea level and when oxygen supply is affected at high altitude.
The success of the drug is explained by a biochemical similarity between the penis and the lungs. Both contain a large amount of phosphodiesterase, an enzyme that limits men's erections and constricts blood vessels in the lungs, meaning that sildenafil, with its ability to stop the effects of this enzyme, cannot only help men to maintain erections, but can also allow better circulation in the walls of the lungs.
Dr Friedrich Grimminger, who led the study, told the BBC that the findings could help sufferers of pulmonary hypertension: 'with this drug, more blood was going through the lung vessels, the gas exchange [the exchange of oxygen and carbon dioxide between the air and the blood in the lungs] improved, and the heart's pumping capacity could be raised.' A patient with the condition who was given sildenafil said: 'it was good to be able to breathe freely again and no longer have that oppressive feeling on my chest.'